The extension author does not collect any data. At all.
Some data will be collected by third parties as you consume their service via the extension.
fip.fr (owned by Radio France, a french public service) might collect data while fetching the playlists and/or streaming audio from their servers.
Read Radio France data protection policy.
last.fm (owned by CBS Interactive, an north american private company) might collect data if you enable the scrobbling feature after connecting your last.fm account.